Published online by Cambridge University Press: 04 February 2011
A synthetic hectorite nanoclay, Laponite®, with a disc shape (20 – 30 nm in diameter and 1 nm in thickness) was used as a model nanoparticle to prepare dispersions in water and different organic solvents. Although up to 20 wt% of nanoclay can be dispersed in water to form a low-viscosity stable colloidal sol, dispersions in organic solvents behave differently. The effect of the dielectric constant of the medium on the viscosity of the dispersion was studied systematically using two series of water-organic solvent miscible blends. Changes in the rheological behavior of the dispersions suggest that the dielectric constant of the organic solvent is a determining factor in the sol-gel transition of a nanoclay-containing nanofluid.